1. Industrial Field of the Invention
The present invention relates to a packaging structure of work stations, personal computers and electronic appliances of similar structures such as word processors (such apparatus will be all referred to as small-sized computers in this specification) and, more particularly, to a packaging structure of small-sized computers of lap-top types, desk-top types and notebook types.
2. Description of the Prior Art
Recently, the above-mentioned small-sized computers have been remarkably improved in their compactness and computing speed. Accordingly, amounts of generated heat by LSI chips and the like tend to increase, and it has been an extremely important subject to improve the cooling efficiency. Conventional small-sized computers of this kind are not provided with special cooling means, and heat generated by heat generating portions is cooled through natural heat radiation in many cases. One of such conventional examples is disclosed in Japanese Utility Model Unexamined Publication No. 62-10494 (a packaging structure of a printed wiring board). In this example, a board on which electronic component parts generating heat are mounted is inclined at an angle to promote natural convection. On the other hand, because the generated heat amounts are increased, as described above, it is necessary to improve the cooling efficiency actively, and new trials have been lately observed in relation to cooling methods. One example of such trials is disclosed in Japanese Patent Unexamined Publication No. 64-2397 (a cooling structure of an electronic circuit package) in which a liquid coolant is used instead of the cooling air and contacted directly with heat generating portions so as to cool them. This method is intended to improve the cooling efficiency by a large extent by use of liquid. Although there are also many known examples of methods utilizing the air, most of them are forcible air-cooling methods with fans, in which shapes of heat radiation fins and air passage structures are contrived for improvement.
In the case of a small-sized computer, the following three factors are particularly important as basic requirements: (a) it is compact; (b) it has a light weight; and (c) it does not consume power more than necessary. From such a standpoint, air-cooling without extra devices is very favorable as a cooling method, and further, natural air-cooling without fans is the best. However, the above-described example disclosed in Japanese Utility Model Unexamined Publication No. 62-10494 is a natural convection cooling method, and this method has a characteristic that the upper limit of heat radiation quantities is determined by temperature and areas of heat radiation surfaces. This conventional example is intended to realize the improvement within the range of the characteristic, and itself by a great extent. Moreover, the latter of the two conventional examples described above is not a structure which sufficiently satisfies the above-mentioned requirements (a)-(c), and it is not necessarily satisfactory as a small-sized computer which must have a low electricity demand and low costs.